Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

606
FXUS63 KLOT 171148
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
548 AM CST Sat Jan 17 2026

.KEY MESSAGES...

- Two clipper systems will bring accumulating snow and slippery
  travel conditions this afternoon/evening and again Sunday
  afternoon/ evening.

- Bitterly cold conditions are expected Sunday night through
  Tuesday morning with wind chills 15 below to 25 below zero
  possible Monday morning.

&&

.DISCUSSION...
Issued at 227 AM CST Sat Jan 17 2026

As the main upper level low slowly lifts northeast and opens
today, another upper low is forecast to move across across the
area this afternoon into this evening, when it too begins to
weaken. Models are in general agreement with a period of light
snow spreading and developing across the area this afternoon,
continuing through mid evening and then dissipating by late
evening. Not much moisture to work with in this dry airmass, but
these low qpf events can still be impactful, especially with
the cold temps in the upper teens/lower 20s expected today and
accumulation on untreated surfaces. Have increased pops into the
70-80% range for areas along/north of I-80. Snow amounts will
likely be under an inch with just a dusting further south.

Next system arrives Sunday afternoon ahead of a blast of arctic
air and similar to today`s system, should be a high pop/low qpf
event. Boosted pops to likely for the northern half or so the
cwa for Sunday afternoon/evening. Snowfall with this system
could be in the one inch range, perhaps 1-2 inches across far
northeast IL, to a dusting across the south. Similar temps in
the upper teens/near 20 will likely allow for accumulation on
untreated surfaces. Winds begin to increase as the snow ends
Sunday evening. With gusts possibly into the 30 mph range, some
blowing snow will likely result even after the falling snow has
ended.

Temperatures will be diving Sunday night into Monday morning and
lows around zero in the northwest to low single digits above
zero elsewhere look on track. The strong winds will push wind
chills as low as 25 below zero across the northwest to 20 below
to 15 below zero for the rest of the area. Too early for any
cold weather advisories, but if these trends continue, will need
to consider one for the northwest cwa Monday morning. Highs
barely rebound in the upper single digits/low teens Monday with
lows back in the low single digits Tuesday morning, possibly
just below zero across the northwest. Winds will have diminished
quite a bit by Tuesday morning, but possibly still in the 10
mph range with wind chills 5 below to 15 below zero possible.

Rather good consistency in the models and their ensembles for a
brief moderation of temps Tuesday into Wednesday ahead of a
clipper system moving across the Great Lakes region. High temps
on Tuesday back in the 20s and possibly upper 20s/lower 30s on
Wednesday. Still some uncertainty for precip chances across the
local area Tuesday night into Wednesday morning with this
clipper. Blended guidance now has chance pops for the northern
half or so of the area and that seems reasonable for now.

There remains quite a bit of uncertainty for the end of next
week into next weekend with the potential for an active pattern
for or near the local area. While the ensembles still show a
decent spread in possibilities, this time period has looked
active for the past week. Regardless of whether precip develops
for the local area, current trends favor a continued cold/very
cold pattern. cms

&&

.AVIATION /12Z TAFS THROUGH 18Z SUNDAY/...
Issued at 548 AM CST Sat Jan 17 2026

- A period of snow expected later this afternoon through the
  evening with associated MVFR to at times low-end IFR VSBYs.

Skies have mostly cleared out early this morning with VFR
conditions expected for at least the next few hours. There is
the potential that a thin layer of MVFR stratus redevelops
through the morning, though confidence in this occurring remains
on the lower side. Have held onto TEMPO groups for MVFR CIGs
and flurries (P6SM -SN) for late morning into early afternoon
but it is possible these fail to fully materialize.

An elongated area of snow extending from northwest IA to
southeast WI is still expected to gradually pivot southeast
across the area during the afternoon, arriving earliest at RFD
(~18Z), DPA/ORD/MDW (~20-21Z), and latest at GYY (~22Z).
Guidance has trended a bit later with the onset, but overall
expect the snow to begin filling in across the area toward mid
afternoon and continue through the evening with associated MVFR
to at times low-end IFR VSBYs (brief dips to 1SM can`t be ruled
out). The character of the snow will be light and fluffy and
will more readily accumulate on pavement given temperatures will
be in the upper teens to around 20 degrees during the snow.
Forecast snowfall totals are generally in the 0.5 to 1" range,
with locally higher amounts possible if the snow is slower to
exit overnight. Non-accumulating flurries may then persist for
much of the overnight hours wherever low stratus remains
overhead.

Winds will remain breezy out of the W to WSW with gusts in the
20-25 kt range through the period.

Petr

&&

.MARINE...
Issued at 330 AM CST Sat Jan 17 2026

A gale watch is in effect late Sunday night through Monday
afternoon for the IL and IN nearshore waters.

An arctic cold front will move across the area Sunday night
bringing much colder temperatures and strong winds to the
region, with a period of gales expected late Sunday night
through at least midday Monday. Freezing spray is also expected,
especially for the IN nearshore waters. cms

&&

.HYDROLOGY...
Issued at 253 PM CST Fri Jan 16 2026

The upcoming extended period of very cold temperatures will likely
result in the rapid development of ice on area rivers and streams
which may increase the chance of localized ice jam flooding. Last
week`s heavy rainfall has resulted in increased streamflow in
several basins, including the Fox, Des Plains, and Illinois River
basins. This higher streamflow will result in a greater potential
for freeze up ice jam flooding.

- Izzi

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 9 PM CST this evening for Winthrop
     Harbor IL to Gary IN.

     Gale Watch from late Sunday night through Monday morning for
     Winthrop Harbor IL to Gary IN.

     Small Craft Advisory until 3 AM CST Sunday for Gary to Burns
     Harbor IN-Burns Harbor to Michigan City IN.

     Gale Watch from late Sunday night through Monday afternoon for
     Gary to Burns Harbor IN-Burns Harbor to Michigan City IN.

&&

$$

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